**4. Conclusions**

The anaerobic digestion process was stable at an OLR of 1 gVS/(L·d), with a specific production rate of 163 ± 28 mL CH4/(gVS·d). However, the increment of the OLR up to 2 gVS/(L·d) resulted in total exhaust of the methane production. The increment in the total and soluble organic matter, especially the increment in the propionic acid concentration up to 1486 mg/L, described an overloaded inhibition process. Regardless of the OLR, the concentration of phenolic compounds was always lower than the inhibition limits. An economic analysis showed that the combination of the steam-explosion recovery of phenols and the anaerobic digestion, under stable conditions, could generate high profitability, which would still be profitable for a phenol extract price higher than 42.2 €/kg. Therefore, steam-exploited OMSW could be a suitable substrate for anaerobic digestion at the correct OLR.

**Author Contributions:** Conceptualization: A.S., F.G.F., B.A.-F., G.R.-G., S.L., J.F.-B. and R.B.; Methodology: A.S., F.G.F., B.A.-F., G.R.-G., S.L., J.F.-B. and R.B.; Validation: A.S., F.G.F., B.A.-F., G.R.-G., S.L., J.F.-B. and R.B.; Formal Analysis, A.S., F.G.F., B.A.-F., G.R.-G., S.L., J.F.-B. and R.B.; Investigation: A.S., F.G.F., B.A.-F., G.R.-G., S.L., J.F.-B. and R.B.; Resources: A.S., F.G.F., B.A.-F., G.R.-G., S.L., J.F.-B. and R.B.; Data Curation: A.S., F.G.F., B.A.-F., G.R.-G., S.L., J.F.-B. and R.B.; Writing—Original Draft Preparation: A.S., F.G.F., B.A.-F., G.R.-G., S.L., J.F.-B. and R.B.; Writing—Review & Editing: A.S., F.G.F., B.A.-F., G.R.-G., S.L., J.F.-B. and R.B.; Supervision: F.G.F. and R.B.; Project Administration: F.G.F. and R.B.; Funding Acquisition: F.G.F. and R.B.

**Funding:** This research was funded by the [Spanish Ministry of Economy and Competitiveness] through Project gran<sup>t</sup> number CTM2014-55095-R and the Ramon y Cajal Programme (RyC 2012-10456). Sergio <sup>L</sup>ópez acknowledges the financial support from the 'V Own Research Plan' of the University of Seville (VPPI-US) for his research contract. This contracts is cofunded by the European Social Fund.

**Acknowledgments:** The authors wish to express their gratitude to. Ainoa Botana for her assistance to this research.

**Conflicts of Interest:** The authors declare no conflict of interest.
